This project concerns a specific developmental language disorder: specific expressive language delay (ELD). ELD is characterized by a substantial delay of expressive language compared with receptive language and IQ. Estimated of the incidence of this disorder in the general population of preschool children range up to 6%. Typically, ELD improves spontaneously or disappears as children reach school age; as a result, many professionals have the view that it does not need to be treated. Countering this are several lines of research indicating that long term unfavorable consequences such as reading problems, school adjustment problems, and psychiatric disorders are associated with early ELD. Very little is known of the causes, correlates, and treatment of ELD. This research aims to determine 1), if there are differences in the social, medical, and linguistic histories of children with ELD, compared with non-delayed controls; 2), if there are current differences in the home linguistic environments of children with ELD. compared with non-delayed controls; and 3), if ELD can be treated by supervised modifications in the home linguistic environment. We will address these aims by studying a sample of 24 ELD children in the age range of 24 to 36 months of age and comparing them with a control group, and by instituting a therapy intervention which will be assessed by comparing a group who receives it immediately with a group who receives it after a wait. A detailed family history, extensive home audio recordings, and a variety of standardized tests of linguistic ability will be part of our procedures. Our long-term objectives are to understand the causes of ELD, to be able to treat it, and to understand the role of the linguistic environment in the acquisition of language by all children. The scientific disciplines in this work are speech and hearing sciences, psychology, pediatrics, and linguistics.